The present invention is directed to solar collectors, articles for mounting solar collectors on a support structure, and methods of employing or making such collectors and articles.
Solar modules, i.e., solar electrical modules (photovoltaic modules) and solar thermal modules, are of great importance, particularly in light of limitations and environmental concerns associated with other sources of energy.
As an example, especially photovoltaic (PV) modules, are conventionally mounted on roof surfaces by bolting or screwing to the roof structure a solar collector including a solar module frame and one or more solar modules mounted on the frame, such frames typically being formed of metal, most commonly aluminum. The roof structure usually contains roof rafters and a plywood base which is nailed to the roof rafters. In many cases, a surface material, e.g., asphalt shingles may be attached to the exposed side of the roof structure. Roof structures, e.g., of plywood, generally have coefficients of thermal expansion which differ significantly from those of the solar module frames, e.g., frames made of aluminum. Extreme differences in thermal expansion between the roof structure and the frame result, especially over the course of winter/summer and day/night cycles. These differences in thermal expansion result in substantial stresses and can result in undesirable loosening of the bolts and/or screws, potentially causing a variety of problems, including water leakage through the roof structure and/or rotting of the surrounding wood, in addition to degradation of the strength of the attachment of the frame to the roof structure.
In larger solar collector installations, and with substructure framing of material with high expansion coefficients (e.g., aluminum is often used because of its light weight and high tensile strength), the difference in expansion can easily amount to more than one centimeter for solar collectors extending over more than 10 meters in width or height, assuming that the substructure reaches minimal temperatures (e.g., in winter) of xe2x88x9210xc2x0 C. and maximal temperatures (e.g., in summer of 80xc2x0 C. In addition to such a large annual differential thermal expansion cycle, a daily cycle (e.g., in the summer, where the difference between the low temperature at night and a high temperature in a sun-exposed midday can readily reach more than 50xc2x0 C.) can also cause an unacceptably large stress on bolts or screws. This differential expansion can cause severe damage to the roof structure. Such damage may go unnoticed for many years, since it may not be readily physically observable, e.g., because the damage is hidden beneath the solar modules. As a result, while significant damage may occur in the initial temperature cycle, such damage can also accumulate over time, producing costly damage in the roof structure, as well as a potential for the collectors to become loose and possibly dislodge from the roof structure.
Conventional applications have employed several much smaller frames that are spaced from each other appropriately to absorb the differential thermal expansion, thereby reducing, but not eliminating, the stress around each bolt or screw. Thermal expansion and/or contraction of such applications generally results in the presence of uneven spaces between collectors. Collectors are desirably mounted as closely together as possible in order to maximize solar collection area, and as a result, even small differences in spacings between collectors sharply detract from the aesthetic qualities of the arrangement of collectors.
Another factor which affects the aesthetic qualities of an arrangement of solar modules is the distance between the solar modules and the support structure (e.g., a roof or wall). With larger distances from the modules to the support structure, non-uniformities in the modules and/or in the mounting hardware are magnified, increasing the negative aesthetic effects of the non-uniformities brought on by temperature changes.
Despite the variety of conventional assemblies which have been used to mount countless solar modules, there remains a need for articles which can be used to reliably mount a solar module on a support structure of any construction, while further reducing or eliminating differential thermal expansion-induced mechanical stresses between the support structure and the frame of the solar collector. There also remains a need for articles which can be used to mount an array of solar modules on a horizontal, tilted or vertical structure surface and provide a homogenous, continuous appearance. There is also an ongoing need for articles which can be used to mount solar modules and which are of a minimum size (thereby minimizing material costs, simplifying handling, reducing weight and reducing shipping costs), which are readily packaged, which are quickly and easily installed, and in which parts can be easily replaced, if ever necessary. The articles and methods of the present invention, as described herein, satisfy these needs.
In accordance with the present invention, there are provided solar module brackets and profile channels as described herein.
For mounting one or more solar module on a support structure, two or more profile channel engagement hooks are attached to or integral with a frame on which the solar module is mounted. Two or more profile channels are attached to or integral with the support structure, e.g., a roof structure, each profile channel having at least one opening. To mount the solar module on the support structure, each profile channel engagement hook is engaged in an opening in a profile channel such that a neck portion of each profile channel engagement hook extends through the opening in the profile channel. Each profile channel preferably comprises at least two holes, so that a hardware connector may be inserted through each of the holes, the hardware connectors attaching the profile channel to the support structure.
In accordance with the present invention, differences in thermal expansion do not result in unacceptable mechanical stresses because the profile channel engagement hooks have sufficient room to move within the openings in the profile channels. In addition, in a preferred aspect of the invention, one or more of the holes are elongated, and the difference between the thermal expansion of the profile channel and the thermal expansion of the support structure results in movement of one or more of the hardware connectors within the elongated opening in which it is mounted, thereby reducing or avoiding thermal expansion-induced stress between the profile channel relative to the support structure.
The present invention thus further provides an array of solar modules mounted on a horizontal, tilted or vertical structure surface, providing a homogenous, continuous appearance. The articles used to mount solar modules reduce material demand by avoiding the need for any horizontal interconnecting frame material. In addition, the articles of the present invention are easily shipped because they include simple linear articles. Also, the installation of the articles for use in mounting of solar modules is very simple, and individual pieces can be readily replaced, if ever necessary.
There are also provided methods of making such solar collectors and methods of mounting such solar collectors on support structures.